Chapter 5.3 / Anthropogenic Contributors to Climate Change

Anthropogenic Contributors to Climate Change

Anthropogenic Contributors to Climate Change

Since the start of the Industrial Revolution, humans have engaged in a range of behaviors (e.g., burning fossil fuels as an energy source and deforestation) that have increased the release of carbon dioxide into the atmosphere. Scientific consensus is that these behaviors are interrupting the carbon cycle and contributing to long-term increases in the amount of greenhouse gases in the atmosphere.

We are releasing carbon from ancient carbon stores so quickly that the natural processes in place to capture and store it cannot keep up with the release. As a result, there is an imbalance in carbon dioxide levels in the Earth's spheres. This imbalance of CO2 levels is mostly in the atmosphere and hydrosphere.

Additionally, as we cut down large sections of forest we are removing one of the major processes in the carbon cycle designed to remove CO2 from the atmosphere (through the photosynthesis of the trees).

The graphic above is popularly known as the “hockey stick” graph of global temperature change over the past 1000 years. The figure clearly illustrates the drastic nature of recent climate change and the rapid change in mean global temperatures since the mid-1800s.

Recent Climate Trends

There are many different factors – some natural and some not – contributing towards global climate change. However, the scientific community widely agrees that, "Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. Recent climate changes have had widespread impacts on human and natural systems."

Ninety-seven percent of climate scientists agree that climate-warming trends over the past century are very likely due to human activities, and most of the leading scientific organizations worldwide have issued public statements endorsing this position.

So what are humans doing to induce climate change?

The combination of exploding population, economic growth and 150 years of industry based on fossil fuels has brought about our rapidly warming climate.

A massive amount of carbon has been sequestered or stored underground, in many forms including coal, oil, and natural gas, which we are now burning for transportation, power generation, and industrial process.

Millions of years ago decaying organic matter was buried by sediments and in the heat and pressure underground became coal, oil, and natural gas.

When these materials are burned for energy, it releases the sequestered carbon and throws Earth’s carbon cycle out of balance.

Electricity Generation

Many students are unaware of the relationship between electricity generation and carbon dioxide production. This section provides an overview.

Electrical Energy Sources

US Electricity Generation by Fuel Type

There are many different ways to heat water to create steam to produce electricity. The chart above show the sources of energy used in the United States to produce electricity. Coal is the most common energy source used to generate electricity in the United States.

Globally, more than 40% of all carbon dioxide emissions come from burning coal.